[aprssig] Another 60M APRS-over-VARA Road Test Tomorrow

[Stephen H Smith]

On 12/15/2023 7:07 PM, Michael Ford wrote:
> Hi Stephen,
> It's great to see experimentation in amateur radio, including the rise of 
> APRS on VARA HF over the last few months.
>
> However, given the FCC's current review of the 60m band and its allocations 
> for amateurs, I'm wondering how wise it is to perform this experiment on 60m 
> and whether it might jeopardize the availability of this resource.  Here are 
> some things I wonder about in this context:
>
> * With your TinyTrack 3 and with UIView, how are you ensuring that the 
> frequency is clear before these stations transmit on their cycles, especially 
> where amateur radio is a secondary use of the 60m band?


The same way anyone else using 60M does.  I have a monitor speaker on the 
FT-891 -- I can hear anything/everything going on on the channel and can stop 
my transmissions at any time.

By using manually-initiated beaconing.   The TinyTrack has a pin for a 
manually-initiated transmission. It was originally intended for "Mic-E" 
burst-on-unkey for voice transmissions on VHF.  I have connected a push-button 
to this pin to fire off a transmission on demand, whenever I want.  The Mic-E 
setup would be uniquely well suited for 60 meters EMCOMMS operations, as on two 
meters,  since 60 meters is the only HF band where voice and data can be on the 
same frequency.  Imagine every unit in a disaster net on 60 being able to 
precisely report their exact location to net control at the end of each voice 
transmission.


>
> * Does it make sense to tie up one of the five available channels on 60m for 
> 4-1/2 hours? I think the same question would be asked if it were an SSB 
> ragchew.  Do you have the ability to know if someone else needs to use the 
> channel and give way?


1)  YES. I have a monitor speaker on the FT-891 -- I can hear 
anything/everything going on on the channel and can stop my transmissions at 
any time.

2)  The volume of traffic on 60M is very low, especially in the daytime.

3)  The effective radiated power of 50 watts into a hamstick-type mobile 
antenna is very low - probably less than 2 watts.  Any fixed station with a 
half-way decent antenna would have no trouble talking over me if needed.


>
> * What's the determination as to whether this is a station under local 
> control (allowed on 60m) or under automatic control (not allowed on 60m)?


Because I am in the driver's seat (literally) less than two feet from the 
Panasonic Toughbook CF-51 mobile laptop generating the transmissions.   The 
home station is a RECEIVE-only igate - it is not generating any transmissions 
at all.


>
> * Does this experiment lead others to start using automatic APRS beacons 
> and/or digipeaters on 60m?


No automatic transmissions or digipeaters expected or encouraged.  Digipeaters 
are strongly discouraged on any HF band, since:

 1. Propagation on HF is so unpredictable and variable  that digis are not a
    useful way of expanding predictable coverage, as they are on VHF.

 2. DIgipeating automatically cuts the channel capacity in half, since the
    original transmission and the digipeat each take up a time slot.

 3. Transmissions are occupying a regional or continental area on HF, compared
    to perhaps a county-size area on VHF.

I am only trying to encourage manually-originated beacons, and MIc-E 
"tail-gating" of voice transmissions.


>
> * Would 40m or 80m be a better choice of band for this experiment, especially 
> where they have subbands for the use of automatic stations?


Again no automatic stations are involved.

As mentioned above, 60m is uniquely well suited to this application due to 
voice/data possible on the same frequency.

The fixed-frequency channelized operation on 60 meters is unique on HF. Makes 
it easier for users to be on the "exact frequency".

80 meters is plagued by more noise and lack of standard channels (so other 
un-related stations often are transmitting randomly "half-off" your channel. 
Perhaps most importantly, simple HF mobile antennas like Ham Sticks are even 
MORE horribly inefficient on 75/80 than they are on 60. (The 7-8-foot Hamstick 
whip is a shorter proportion of the natural full quarter-wave-length on 80 than 
it is on 60. )

40 meters often has huge skip zones.  Especially at night, you can't hear 
anything CLOSER than 500-700 miles away.

60 meters has excellent NVIS propagation for 0-300 miles or so coverage most of 
the time. (I am interested in state-wide or regional coverage -- not DX! )


-------------------------------------------------------------------------------
Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page: http://wa8lmf.net

"Studio B" Ham Shack on Wheels
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-- APRS over VARA  --
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